CHANGE IN DIRECTION OP EARTHS MAGNETIC FIELD. 
331 
Lat. 31° 15' N. SHANGHAI. Long. 121° 29 / E. 
Year. 
Magnetic 
dip or in¬ 
clination. 
Authority. 
Observer. 
Where recorded. 
1843........ 
O 
+44.75 
Sir E. Home. 
Report for 1876 of the Zi-Ka-Wei Observatory. 
1858. 
+45.35 
Novara expedition 
. 
Phil. Trans. Royal Society, Part I, 1875. 
1872.3 .... 
+46.24 
Shadvvell. 
Phil. Trans. Royal Society, Part I, 1877. 
1873.3 .... 
+46.32 
.do..... 
Do. 
1875.5 .... 
+46.26 
Jesuit missionaries.. 
Le Magnetisme Terrestre a Zi-Ka-Wei, Chine, 
par Marc Dechevrens, S. J., Directeur de 
TObservatoire. 
1876.5 V... 
+46.23 
.do. 
. 
Do. 
1877.5 .... 
+46.23 
..do. 
. 
Do. 
1878.5 .... 
+46.22 
.do. 
. 
Do. 
1879.5 .... 
+46.25 
.do. 
Do. 
1880.5 .... 
+46.27 
.do. 
. 
. 
Do. 
1881.5 .... 
+46.28 
.. do. 
. 
Do. 
1882.5 .... 
+46.30 
.do. 
. 
Do. 
1883.5 .... 
+46.30 
.do. 
. 
Do. 
18S4.5 .... 
+46.32 
. 
. 
Do. 
1885.5 .... 
+46.30 
.do. 
Do. 
188G.5 .... 
+46.28 
.do. 
. 
. 
Do. 
1887.5 .... 
+46.27 
.do. 
. 
. 
Do. 
1888.5 .... 
+46.23 
Do. 
1889.5 .... 
+46.25 
. 
Do. 
1890.5 .... 
+46.19 
.do. 
.. 
. 
Do. 
1891.5 .... 
+46.10 
.do. 
. 
Do. 
1892.5 .... 
+46.12 
.do. 
. 
Do. 
1893.5 .... 
+45.99 
.do. 
Do. 
1894.5 .... 
+46.01 
. 
Do. 
Year. 
Observed. 
Computed. 
O-C. 
o^c 2 . 
1843. 
o 
+44.75 
o 
+44.63 
+0.12 
0.0144 
1858. 
+45.35 
+45.67 
—0.32 
0.1024 
1872.3 .... 
+46.24 
+46.18 
+0.06 
0.0036 
1873.3 .... 
+46.32 
+46.20 
+0.12 
0.0144 
1875.5 .... 
+46.26 
+46.24 
+0.02 
0.0004 
1876.5 .... 
+46.23 
+46.24 
—0.01 
0.0001 
1877.5 .... 
+46.23 
+46.26 
—0.03 
0.0009 
1878.5 .... 
+46.22 
+46.26 
—0.04 
0.0016 
1879.5 .... 
+46.25 
+46.27 
—0.02 
0.0004 
1880.5 .... 
+46.27 
+46.27 
+0.00 
0.0000 
• 
1881.5 .... 
+46.28 
+46.27 
+0.01 
0.0001 
1882.5 .... 
+46.30 
+46.27 
+0.03 
0.0009 
1883.5 .... 
+46.30 
+46.27 
+0.03 
. 0.0009 
•Probable error of a single observation = ± 2 '.4 . 
1884.5 .... 
+46.32 
+46.25 
+0.07 
0.0049 
1885.5 .... 
+46.30 
* +46.25 
+0.05 
0.0025 
1886.5 .... 
+46.28 
+46.24 
+0.04 
0.0016 
1887.5 .... 
+46.27 
+46.23 
+0.04 
0.0016 
1888.5 .... 
+46.23 
+46.21 
+0.02 
0.0004 
1889.5.... 
+46.25 
+46.19 
+0.06 
0.0036 
1890.5 .... 
+46.19 
+46.17 
+0.02 
0.0004 
1891.5 .... 
+46.10 
+46.15 
—0.05 
0.0025 
1892.5 .... 
+46.12 
+46.12 
+0.00 
0.0000 
1893.5 .... 
+45.99 
+46.10 
—0.11 
0.0121 
1894.5 .... 
+46.01 
+46.07 
—0.06 
0.0036 
0.0733 
Empirical equation for determining the inclination for any year: I = 46°. 13 -f- 
0.0251 (t — 1870) — 0.00112 {t — 1870) 2 . 
